Pollution characteristics, sources, and health risk assessment of human exposure to Cu, Zn, Cd and Pb pollution in urban street dust across China between 2009 and 2018

Since heavy metal pollution is widespread in street dust in China, the effects of heavy metals in street dust on human health cannot be ignored. However, studies estimating heavy metal pollution in street dust nationwide are limited. In this study, the concentrations of Cu, Zn, Cd and Pb in street dust at 3877sites throughout China were obtained from the published scientific literature. Based on these data, the contamination levels, spatial distributions, sources and potential health risks of heavy metals in street dust were comprehensively estimated. The results revealed that Cu, Zn, Cd and Pb levels are generally higher in the southeast provinces than in northwest China. In addition, traffic emissions and industrial activities are determined to be the two main sources of heavy metal pollution in street dust. The health risk assessment indicated that ingestion is the most important pathway of exposure to metal pollution in street dust for both children and adults, followed by dermal contact and inhalation. The spatial distribution of health risks suggested that the health risks are more serious in southeast China than in northwest China. The noncarcinogenic risks posed by Pb are relatively higher than those posed by the other three metals for both children and adults. Meanwhile, none of the hazard index (HI) values exceeded the safe level (1.0), with the exception of Pb in Daye city for children (HI = 1.074). The HI values for children were higher than those for adults. Therefore, children should be prioritized for protection from heavy metal pollution.